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Questions tagged [graphene]

The properties of graphene and their modelling.

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Phonon dispersion calculation of graphene with ASE

I'm trying to use the package ase.phonons to calculate the dispersion relation bands and the DOS, I followed the example of the documentation for Al and went well for the diamond case. For some reason,...
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How to relate the degree of oxidation with the C/O ratio for the nanomaterials like graphene oxide?

I am currently working on the molecular modelling of Graphene oxide. It has different oxygen containing surface functionalities, so different degrees of oxidation. I am wondering if there is anyway to ...
NM_curious's user avatar
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Can I use the convergence test results of ecutwfc, ecutrho, and k points obtained from a 2x2 graphene supercell for a larger graphene supercell?

Recently, I conducted convergence tests (ecutwfc, ecutrho, and k points) for a 2x2 graphene supercell, yielding results of 120 Ry, 300 Ry, and 10x10x1 respectively. (Here, we considered convergence ...
Thejan Hasaranga's user avatar
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cif file of psi graphene [closed]

What mysterious properties lie within the crystalline structure of ψ-graphene, the enigmatic 2D carbon allotrope adorned with intricate 5-6-7 carbon ring patterns, that endows it with the crown of the ...
Jose Antony's user avatar
4 votes
1 answer
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Exploring Phonon Dispersion in Two-Dimensional Materials: Analytical Techniques and Mode Identification

How can one analyze the phonon dispersion of 2D materials like graphene to discern specific curves corresponding to particular phonon modes, such as acoustic or optical, as well as longitudinal and ...
Farah Shehzadi's user avatar
1 vote
1 answer
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Number of electrons per cell

I aim to do a HF-like calculation on a 2D graphene layer. What is the number of electrons per cell? Edit: There are six carbon atoms per cell.
mle's user avatar
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Where can I read about Valleytronics?

Where can I read about Valleytronics? Are there any good books or review papers or influential papers on this topic? The question was also posted at the Physics site.
Rich Hard Fine Man's user avatar
2 votes
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transiesta convergence for defective graphene [duplicate]

I have a defective graphene system - 94 atoms (32 in both electrodes and 30 in scattering). The transiesta run is just not converging. I get this message: ...
MANOJ N MATTUR's user avatar
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Transiesta with siesta version 4.1.5 not converging

Good evening everyone, With previous Transiesta versions, we would not have issues with finding the transport involving graphene. However, this was not the case with the latest version. We tried: ...
abed haidar's user avatar
1 vote
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Transiesta convergence issue [duplicate]

I have a graphene system (94 atoms - defective graphene) I was able to converge both right and left electrode runs in just 8 iterations. But the scattering run (transiesta) is not converging even ...
MANOJ N MATTUR's user avatar
6 votes
1 answer
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How accurate is DFTB+ in reproducing DFT result?

I am trying to study the shifts in the Fermi level of a graphene - ssDNA hydrid system, depending on the identity of the ssDNA. The structures are obtained from a classical MD simulation, and cannot ...
Hemanth Haridas's user avatar
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Theoretical Capacity of g-C3N4?

I was reading a paper that stated: For example, graphitic carbon nitride (g-C3N4) is considered a potential anode material for lithium ion batteries due to its easy accessibility, low cost and large ...
lzzard's user avatar
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Convergence issues in DFTB+ calculations?

I am trying to calculate the Fermi level of a DNA-graphene system. I was able to get the calculations for graphene and DNA strand to converge separately. However, when I try to calculate the same for ...
Hemanth Haridas's user avatar
3 votes
1 answer
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Error in TranSIESTA: "The electrode down-folding region is 0 in the device region"

When I run a tranSIESTA calculation, the SCF converges, and the TBtrans output shows the following error: ...
Hananab's user avatar
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Simulated STM Image with Quantum-ESPRESSO's pp.x

Context: I am an undergraduate "self-taught" noob when it comes to QE. (I've just been using online resources and textbooks thus far.) There are no QE or DFT experts at my university (I have ...
D_C's user avatar
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Why can graphene nanoribbons be safely used as electrdes, despite having a finite band gap?

I was following the following this tutorial. As far as my understanding goes, one should use bulk-like metallic electrodes to avoid problems with screening and Fermi-level definition. Can someone ...
Laura's user avatar
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Transiesta SCF not converged [duplicate]

I have encountered a convergence problem in my structure device in Transiesta calculation, the calculation doesn't converge. Recently I try to decrease the mixing weight parameter to 0.00001. For some ...
Hananab's user avatar
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What causes atoms to not interact in LAMMPS? [closed]

I am trying to set up a LAMMPS simulation for depositing graphene on a nickel substrate. I am using ReaxFF forcefield. However, the carbon atoms just pass through the nickel atoms. Can anyone help me ...
Anish's user avatar
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Does laser-induced graphene (LIG) stay functional after being extracted from the substrate? [closed]

So, I've seen some videos about laser induced graphene and its use as either a supercapacitor or as a low-voltage heater. In this video the person only uses two electrodes on each end of the LIG tape ...
Fulano's user avatar
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What are the key things I need to learn before I can simulate graphene growth on a metal substrate using LAMMPS? [closed]

I am planning to conduct an MD simulation research on graphene growth on a metal substrate using lammps. I recently learned to form a crystal lattice using lammps. But I have no idea what to look for ...
Anish's user avatar
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Making a graphene based conductive ink [closed]

I want to make a graphene-based conductive ink with cyclohexanone pr terpinol as the solvent and ethyl cellulose as the binder. How can I do that?
Akshay K's user avatar
18 votes
2 answers
3k views

How to explain to a five year old why "DFT with local exchange–correlation functionals do(es) not describe van der Waals interactions accurately"?

From How do you explain Canada's Trudeau's power-sharing agreement to a five-year-old (American)?: The "explain to a five-year-old" question is a semi-standard format where the answer ...
uhoh's user avatar
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9 votes
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DIY molecular dynamics for Xenes on crystal surfaces; where can I get applicable open-source force field parameters that I can use in my scripts?

The linked question(s) below describes a DIY project to simulate how Xenes (honeycomb nets of atoms like graphehe) behave on single crystal surfaces. Behaviors include rotation, strain, and heigh ...
uhoh's user avatar
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5 votes
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How does the VIBRA module of SIESTA compute IR intensities? [closed]

I am working with Fluoro-Graphene (let's assume a fully relaxed monolayer on the XY plane with 16C-1F cell where the F is "covalently" bound to the graphene on top of it with respect to the ...
Elie H's user avatar
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291 views

How to stack a nanocrystal on top of a graphene slab in ASE?

I'm trying to model a 2D TMD (transition metal dichalcogenide) nanocrystal on a graphene substrate. I know how to generate 2D TMDs through the MX2 module, and I certainly know how to make graphene on ...
the-bfg's user avatar
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6 votes
1 answer
178 views

Help with definitions in k-space twisted bilayer graphene model

I am trying to numerically do calculations using Eq. 8 of MacDonald's simple model for twisted Bilayer graphene. I only want to calculate the Berry phase. However, I don't think I have my definitions ...
TribalChief's user avatar
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4 votes
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158 views

How to design Graphene metasurface using COMSOL? [closed]

I want to simulate a graphene based metasurface using COMSOL. Can anyone tell me the steps of defining Graphene in COMSOL or provide any tutorial for the same?
Anirban Choudhury's user avatar
8 votes
1 answer
139 views

Help with understanding topologically-protected edge states in domain wall systems

Let's say that I have a simple domain wall system for the following Hamiltonian with added on-site potential $M(x)$: $$\tag{1} H(k,M)=-t \sum_{\delta} [\cos(k\cdot\delta)\sigma_x-\sin(k\cdot\delta)\...
TribalChief's user avatar
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11 votes
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Wavefunction magnitudes being degenerate everywhere on parameter space even though energy degeneracies occur at isolated points?

Cross-posted here. Consider the usual simple 2-level gapless graphene Hamiltonian in momentum-space where the energy dispersion is degenerate/gapless at a Dirac point: \begin{equation}\tag{1} {\small ...
TribalChief's user avatar
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10 votes
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What's the past and future of 2D materials since graphene?

Since the discovery of graphene in 2004, two-dimensional (2D) materials have been a hot topic in the community of condensed matter physics, which can be considered as the candidate for next-generation ...
Jack's user avatar
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-4 votes
1 answer
133 views

Has there been research on improving the strength of graphene-based materials?

I read that brittle materials tend to have an observed strength much less than its theoretical strength because they tend to have surface cracks and whatever tension is applied gets greatly magnified ...
Timothy's user avatar
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5 votes
1 answer
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How to separate the band structure of different materials in heterostructures using Quantum ESPRESSO?

So, I know that to calculate surface band structure of a material, you have to take its 2D system eg. single or few-layered. But, how to find the surface band structure in the case of heterostructures....
Ashique Lal's user avatar
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12 votes
1 answer
675 views

Binding energy calculation for Zn atom on armchair graphene slab?

I am trying to repeat the result of this paper for Zn absorbed on the armchair graphene slab. The relaxed top and side structures are the following: The relaxed structure is almost the same as the ...
Jack's user avatar
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12 votes
1 answer
2k views

What does capital sigma followed by an integer (Σn) mean in the context of grain boundaries?

I've just run across a nomenclature for coincidence lattices at grain boundaries which uses a capital greek letter sigma followed by an integer. For example A.D. Rollett's 2016 Grain Boundary ...
uhoh's user avatar
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10 votes
1 answer
352 views

Does the Mermin-Wagner theorem influence the stability of graphene?

Prior to the discovery of graphene, the Mermin-Wagner theorem was used to argue that purely two-dimensional materials would not be stable as two-dimensional order would show logarithmic divergences at ...
pldd86's user avatar
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13 votes
0 answers
448 views

Sample LAMMPS file for graphene growth on a metal surface [closed]

I am working with graphene growth on metal substrates. But I need some sample files to know if I am doing it in the right way because running multiple simulations in LAMMPS takes a lot of time. Can ...
Abdullah Arafat's user avatar
17 votes
1 answer
5k views

How to understand the time-reversal symmetry in graphene?

A lot of references say that the Dirac cone in graphene is protected by inversion and time-reversal symmetries. How can one understand this statement? How can one show explicitly that the gapless ...
JensenPang's user avatar
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21 votes
1 answer
186 views

Why can't I reproduce the behavior of an H-saturated graphene flake?

I'm trying to simulate a graphene flake with its edge C atoms saturated by H atoms, in a temperature ramp from 300 K to 1600 K, using LAMMPS and the AIREBO potential proposed by Stuart et al. in 2000. ...
Gabriel Olguín's user avatar
16 votes
1 answer
1k views

Why is the band gap of graphene "opened" in this VASP calculation?

I used VASP to do the band structure calculation on Graphene. Originally I would expect that the Dirac cone can be observed in the K point. If we watched qualitatively, we can see this behavior. But ...
JensenPang's user avatar
  • 2,883
12 votes
1 answer
576 views

DFT vs tight-binding solutions for a Dirac cone in graphene: Why is the DFT version squeezed?

I'm a beginner at DFT calculations with VASP software. I use it to calculate the band structure of graphene and I obtain the following result: I used it to calculate the band structure of graphene ...
JensenPang's user avatar
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